Method and apparatus for cryogenic air separation
AssigneeL'Air Liquide, Societe Anonyme pour l'Etude et l'Exploitation des Procedes Georges Claude
InventorsYongshun Zhang, Alain Briglia, Xianbiao Zheng
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Abstract
The present disclosure provides a method for cryogenic air separation. In the method, part (b2) of the air (b) is compressed in warm booster (7), cooled in heat exchanger (2) and then divided in two, one part (c1) being compressed in a cold booster(9) driven by one turboexpander (11) in which the other part (c2) of air (c) is expanded, and another part of the feed air is not boosted but is expanded in another turboexpander (6) which drives the warm booster (7). The present disclosure also provides an apparatus for cryogenic air separation.
Claims13
A method for cryogenic air separation, wherein air is separated cryogenically in an apparatus for cryogenic air separation comprising a main air compressor, a main heat exchanger, and a rectification column system which has a low-pressure column operating at a first pressure and a high-pressure column operating at a second pressure higher than the first pressure, the method comprising the steps of:
- compressing a total feed air stream in the main air compressor into a third pressure air stream of a third pressure, wherein the third pressure is higher than the second pressure,
- partially cooling a first part of the third pressure air stream in the main heat exchanger, thereby producing a cooled third pressure air stream, and then expanding the cooled third pressure air stream in a first turboexpander to form a first air stream,
- further compressing a second part of the third pressure air stream in a first booster into a fourth pressure air stream of a fourth pressure, and firstly cooling the fourth pressure air stream in an aftercooler, and then secondly cooling the fourth pressure air stream in the main heat exchanger, thereby producing a cooled fourth pressure air stream,
- further compressing a first part of the cooled fourth pressure air stream after secondly cooled, into a fifth pressure air stream of a fifth pressure in a second booster, thirdly cooling the fifth pressure air stream in the main heat exchanger, and then expanding the fifth pressure air stream from the fifth pressure in a first expansion device to form a second air stream,
- expanding a second part of the cooled fourth pressure air stream after secondly cooled from the fourth pressure in a second turboexpander to form a third air stream, and
- feeding the first air stream, the second air stream, and the third air stream to the rectification column system, wherein at least a portion of the first air stream, the second air stream, and/or the third air stream is sent to the high-pressure column;
- and
- obtaining a liquid output from the rectification column system,
- wherein the first booster is mechanically coupled to the first turboexpander, and the second booster is mechanically coupled to the second turboexpander.
An apparatus for cryogenic air separation, comprising a main air compressor, a main heat exchanger, and a rectification column system which has a low-pressure column operating at a first pressure and a high-pressure column operating at a second pressure higher than the first pressure, wherein the main air compressor compresses a total feed air stream into a third pressure air stream to a third pressure higher than the second pressure, comprising:
- a first turboexpander, configured such that a first part of the third pressure air stream is partially cooled in the main heat exchanger, and expanded from the third pressure in the first turboexpander to form a first air stream;
- a first booster, configured such that a second part of the third pressure air stream is further compressed in the first booster into a fourth pressure air stream;
- an aftercooler, configured such that after firstly cooled in the aftercooler, the fourth pressure air stream enters the main heat exchanger to be secondly cooled;
- a second booster, configured such that a first part of the fourth pressure air stream after secondly cooled is further compressed into a fifth pressure air stream in the second booster, wherein the fifth pressure air stream is then thirdly cooled in the main heat exchanger, and expanded from the fifth pressure in a first expansion device to form a second air stream;
- and
- a second turboexpander, configured such that a second part the fourth pressure air stream after secondly cooled is expanded from the fourth pressure in the second turboexpander to form a third air stream;
- wherein the apparatus is configured such that, the first air stream, the second air stream, and the third air stream are sent to the rectification column system, wherein at least a portion of the first air stream, the second air stream, and/or the third air stream is sent to the high-pressure column, and a liquid output is obtained from the rectification column system,
- wherein the first booster is mechanically coupled to the first turboexpander, and the second booster is mechanically coupled to the second turboexpander.
Dependencies are inferred from the claim text.